This invention relates to a gate driver circuit for MOS gated devices, and more specifically relates to a monolithic gate driver circuit for MOS gated circuit devices, particularly those used in lamp ballast circuits.
Electronic ballasts for gas discharge circuits are coming into widespread use because of the availability of power MOSFET switching devices to replace previously used power bipolar transistor devices. Most electronic ballasts use two power MOSFET switches in a totem pole (half bridge) topology, with the gas discharge tube circuits consisting of L-C series resonant circuits in which the lamp or lamps are connected across one of the reactances of the L-C circuit. The power MOSFET switches are then driven to conduct alternately by inputs from secondary windings on a current transformer, the primary winding of which conducts the current of the lamp circuits. The primary winding current alternates at the resonant frequency of the resonant circuit.
Such prior art circuits have numerous drawbacks. For example, such circuits:
1. Are not self-starting and require a DIAC type device to initially pulse the circuit into operation.
2. They have poor switch times.
3. They are labor intensive due particularly to the need for a toroidal current transformer.
4. The circuits are not amenable to dimming.
5. The circuits are not amenable to mass production manufacture.